1. Field of the Invention
This invention relates to printers, particularly wet ink printers, and more particularly, to an apparatus for, and method of, transporting wet print media out of a printer.
2. Art Background
A common problem with prior art ink jet printers which sequentially print on paper or other media using wet ink, particularly those which print rather rapidly, is that the wet ink may not have sufficient time to dry as it is being manipulated by the printer or prior to the printing of a subsequent sheet and its placement over the prior sheet. The obvious result of this problem is that the print on the prior sheet smears, smudges or is otherwise distorted, and/or the ink is absorbed by the back of the subsequent sheet. Many prior art printer systems simply let the ink smear, which has its obvious undesirable characteristics. One approach to solving the problem of slow paper drying is the use of specially coated, faster drying paper which is more expensive than standard paper. Another approach is the use of a drying device, such as a lamp or heater to accelerate drying time; however, such apparatus makes the printer heavier and more expensive, and sometimes causes buckling of the paper. Yet another approach is a passive drop system in which the paper drops at a relatively slow rate and air dries before dropping. Another approach is to provide substantial margins which permit the paper to be grabbed and controlled at its margins so that the ink is not touched at least while the paper is being handled.
Hewlett-Packard discloses in its U.S. Pat. No. 4,794,859 an ink jet printer which prints and stacks paper in a horizontal plane, and provides an active paper drop mechanism comprising a pair of movable rail members which actively guide the paper down to a collection stack. The rail members support a sheet of paper for a predetermined period of time in order to provide the paper with sufficient time to dry before the rail member releases the paper allowing it to touch the last previously printed page. The rail permits manipulation of the paper without touching the printed portion thereof.
To eject paper from a printer, most printers utilize small rotating drive wheels (pinch rollers) which drive the paper through the printer. These may leave long tracks from wet print. Some devices utilize star shaped wheels made of plastic or metal wherein the points of the star contact the paper. However, even these star shaped drive wheels cause small dots across the paper from the wet ink. Alternatively, the star wheels can be positioned outside the print area, but this requires that the print area be reduced so that the star wheels contact only the margin. The star wheels also cause indents in the paper across the entire page. They are also relatively costly.
Thus, it is desirable to provide a new system and method for transporting wet print media out of a printer which handles and manipulates wet print media without the drawbacks of the prior art systems and methods.